1. Field of the Invention
This invention relates to a fuel tank of synthetic material for motor vehicles and more particularly to its expansion and venting system. It also relates to means to facilitate the automatic positioning of the above assembly, to simplify it and to limit its costs. It also relates to means to give the tank and its ancillary systems a level of reliability according to safety standards in force.
2. Description of the Related Art
The fuel tanks generally now known have within their enclosure an expansion volume that must remain unoccupied by liquid to compensate for fuel and gas expansion in case of heating.
There follows from the above the provision of several gas evacuation pipes coming from the upper part of the tank. These pipes are fastened to the tank in a manner which avoids siphoning during travel. However, this constitutes an assembly constraint, because it requires the piercing of certain obstacles, such as the cross members of the carrying structure, for the passage of said pipes, in order to maintain their continuity. The downward contouring of the pipes past these obstacles could produce the formation of the siphoning that must be avoided.
Another weakness of prior systems resides in the means used to reserve the expansion of volume during filling of the tank and its venting after closing of the cap. These functions are conventionally performed by mechanical check valves that lack reliability and whose cost, including mounting and checking of their various parts, is relatively high.